Gateway laptop MX6440 no OS found

Here we go. Gateway laptop MX6440 xp too vista about 12 years. Shared the vista os from another lap i had a Dell inspirion 1501, which i then sold w/disk. Used the Gateway periodically as i also had a Desktop Compaq presario w/vista oem, and activation id.
Well my Gateway which i probably should replace, but not quite yet has a boot problem. NO OS FOUND. Think i caused shrinking the volumn of the drive, 100gb.
Anyhow i know i could download xp or vista, upgrade too windows 7, cheaply, their no longer supported. However everyone wants too do a download. I think i need the real media cd/dvd, no os found. downloads are too the the drive. can't change the path. any ideas am i wrong.
have 2- valid product keys, but compaq wont allow, using their recovery disks.